Mechanisms for cellular, hormonal and viral regulation of plasma membrane transport systems in mouse fibroblast cultures will be investigated. In order to understand the physiological and functional significance of protein kinase phosphorylation of plasma membrane proteins in nontransformed 3T3 mouse fibroblast cultures and their Simian Virus 40 or chemically-transformed derivatives, transport systems for ions and nutrients will be surveyed for functional linkage to membrane protein phosphorylation using intact cells and their isolated plasma membrane vesicles which catalyze transport. As another model syytem for regulation of membrane transport phenomena, the induction of domes, a manifestation of epithelial fluid transport, will be studied in epithelial cell cultures derived from kidney and from mammary gland. Changes in phosphorylated intracellular and membrane proteins which accompany induction of domes by cyclic AMP, various categories of chemical inducers and specific hormonal stimuli will be analyzed.